As a latent curing agent for a thermosetting epoxy resin composition, a microcapsule-type latent curing agent has been proposed (Patent Literature 1) in which an imidazole compound is held in porous resin particles, which are the product of interfacial polymerization of a polyfunctional isocyanate compound. This latent curing agent is produced by preparing an oil-in-water emulsion formed by emulsifying an oil phase obtained by dissolving a polyfunctional isocyanate compound in ethyl acetate in an aqueous phase obtained by dissolving a surfactant and polyvinyl alcohol as a dispersant in water, and then forming porous resin particles by heating this emulsion to carry out interfacial polymerization of the polyfunctional isocyanate compound in the oil phase. These porous resin particles are recovered, dried, and then dipped in an imidazole compound solution formed by dissolving the imidazole compound in ethanol to make the imidazole compound solution permeate into the porous resin particles. The porous resin particles permeated with the imidazole compound solution are then recovered, washed, and dried to produce the latent curing agent.